EP 1 283 576 A has disclosed an electrical bushing which connects the conductor of a superconductor cable to an electrical supply system. The conductor of the bushing comprises a copper conductor, which is surrounded by a solid electrically insulating layer, for example ethylene-propylene rubber or similar materials.
The known bushing connects the conductor of a superconductor cable to an electrical supply system, the bushing passing through a region having a low temperature, for example liquid nitrogen, a region having a slightly higher temperature (gaseous nitrogen) up to a region at ambient temperature in order to increase the distance between the point at which the conductor of the superconductor cable is connected to the conductor of the bushing and the region at ambient temperature.
With this bushing, problems may result in the event of changes in temperature if, for example, the superconductor cable is brought into or taken out of operation. Owing to the different coefficients of thermal expansion of the conductor material of the bushing (copper, aluminium etc.) and of the insulating material, thermomechanical stresses result which destroy the bushing in the region of the conductor/insulating layer.
DE 26 07 516 A1 has disclosed an electrical cable having a conductor and an insulating layer surrounding the conductor. An interlayer is provided between the conductor and the insulating layer and consists of a material which prevents adhesion of the insulating layer on the conductor and, as a result, makes it easier for the insulating layer to be removed from the conductor.